Here's a free game idea for Zynga. It's called DefectionVille, and you're running a company while trying to stop its executives from leaving. Unfortunately for the social gaming giant, it's losing: The exec exodus continued Tuesday as Zynga CFO David Wehner left the company for Facebook.

Zynga is the undisputed king of social gaming for Facebook and smartphones, and its stock price gives it a market cap nearly as big as video game leader Activision Blizzard. But at less than 5 years old, has the bulldog already jumped the shark?